有a.maths 唔識做

tan5x = cot5x
tan5x=tan(90*-5x)
5x=180n*+(90*-5x)
10x=180n*+90*
x=18n*+9*

2008-06-07 23:39:40 補充：
@﹏@估5到慢過上面個位tim..慢左=﹏=

2008-06-07 23:40:39 補充：
有改地方:

x=18n*+9* ,where n is any integer

tan5x = cot5x
tan5x=tan(90˚-5x)
5x=180n˚+(90˚-5x),where n is an integer
10x=180n˚+90˚
x=18n˚+9˚

tan5x = cot5x
tan²5x=1
5x=180°n+45°
x=36°n+9°, where n is any integer